It is known, especially in the nuclear industry, to use valves, cocks, and clack valves made up of several assembled parts whose outside seal is achieved by means of a peripheral welding, the latter being performed on the projecting lips which are presented by the different parts that make them up.
Consequently, when it is desired, for any reason, for example during malfunctioning, to open a valve provided with such a welding, it is necessary first to eliminate the welding bead, this operation being performed to avoid damaging the valve and particularly its lips to be able to reuse this valve later.
This operation is now still performed by hand with a simple metal-cutting saw. Now, this operation is very delicate and tedious for the operator, because he must work in the joint face of the two lips so as not to damage them and to permit their rewelding. This operation is further performed often under difficult access conditions and most of the time requires several hours.
In French patent No. 2,548 063 a device has already been proposed for cutting the welding of such valves, the device is made up of a support tool in two symmetrical parts delimiting a central opening for the passage of the valve, and provided with grooved rollers to assure the guiding in rotation of this support on the projecting lips of the valve. The cutting tool actually consists of two opposing rotary cutters in the support, between guide rollers, and intended to shear the welding bead. However, this device functions like a pipe-cutter.
Now, because of their dimensions and their assembly, it is inevitable to have a bending of the cutters during their engagement with the metal, so that the cut is never made exactly on the joint face of the lips, which obliges the operator to complete the cut by chance and the metal-cutting saw.
Further, in this known device, the four rollers are all adjustable independently of one another, so that it is difficult to obtain a good concentricity of this device in relation to the valve.
Another cutting device described in the internal journal "Technique en bref" of the Societe EDF functions on the same principle as the device described above, by using two cutting tools working in opposition. In this device the width of the groove of the rollers is greater than the thickness of the lips, so that they rest against the body of the valve and an adjustment in height of the cutting tool is provided to assure a correct positioning of it on the joint face of the lips.
Further, this device is made up of four articulated parts to fit different valve diameters.
Because of these articulations and the multiplicity of adjustments and therefore of play, the device lacks rigidity, which causes breaking of the cutting tools during machining as a result of the bending forces generated on them.
These different devices therefore are not completely satisfactory and, further, do not make it possible to achieve the opening of the valve.